Employee Benefits - Reconciliation of Beginning and Ending Balance of Pension Plan Assets Measured at Fair Value (Detail) - Pension - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Defined Benefit Plan, Change in Fair Value of Plan Assets, Level 3 Reconciliation [Roll Forward]
Beginning of year	$ 20,087	$ 20,128
End of year	13,739	20,087
Level 3
Defined Benefit Plan, Change in Fair Value of Plan Assets, Level 3 Reconciliation [Roll Forward]
Beginning of year	1,651	1,507
Actual gain (loss) on plan assets	68	(45)
Purchases (sales)	9	421
Transfers out	(105)	(232)
End of year	1,623	1,651
Level 3 | Equity securities
Defined Benefit Plan, Change in Fair Value of Plan Assets, Level 3 Reconciliation [Roll Forward]
Beginning of year	0	2
Actual gain (loss) on plan assets	0	(1)
Purchases (sales)	0	(1)
Transfers out	0	0
End of year	0	0
Level 3 | Corporate bonds
Defined Benefit Plan, Change in Fair Value of Plan Assets, Level 3 Reconciliation [Roll Forward]
Beginning of year	0	176
Actual gain (loss) on plan assets	0	(5)
Purchases (sales)	0	1
Transfers out	0	(172)
End of year	0	0
Level 3 | International bonds
Defined Benefit Plan, Change in Fair Value of Plan Assets, Level 3 Reconciliation [Roll Forward]
Beginning of year	0	20
Actual gain (loss) on plan assets	0	0
Purchases (sales)	0	(4)
Transfers out	0	(16)
End of year	0	0
Level 3 | Real estate
Defined Benefit Plan, Change in Fair Value of Plan Assets, Level 3 Reconciliation [Roll Forward]
Beginning of year	972	757
Actual gain (loss) on plan assets	19	(21)
Purchases (sales)	14	197
Transfers out	(3)	39
End of year	1,002	972
Level 3 | Private equity
Defined Benefit Plan, Change in Fair Value of Plan Assets, Level 3 Reconciliation [Roll Forward]
Beginning of year	569	414
Actual gain (loss) on plan assets	30	(19)
Purchases (sales)	(11)	147
Transfers out	(19)	27
End of year	569	569
Level 3 | Hedge funds
Defined Benefit Plan, Change in Fair Value of Plan Assets, Level 3 Reconciliation [Roll Forward]
Beginning of year	110	138
Actual gain (loss) on plan assets	19	1
Purchases (sales)	6	81
Transfers out	(83)	(110)
End of year	$ 52	$ 110